5.11 Function Types

Various types can be defined for function variables. These types are
not used in defining functions (see Procedures); they are used for
things like pointers to functions.

The simple, traditional, type is type descriptor f is followed by
type information for the return type of the function, followed by a
semicolon.

This does not deal with functions for which the number and types of the
parameters are part of the type, as in Modula-2 or ANSI C. AIX provides
extensions to specify these, using the f, F, p, and
R type descriptors.

First comes the type descriptor. If it is f or F, this
type involves a function rather than a procedure, and the type
information for the return type of the function follows, followed by a
comma. Then comes the number of parameters to the function and a
semicolon. Then, for each parameter, there is the name of the parameter
followed by a colon (this is only present for type descriptors R
and F which represent Pascal function or procedure parameters),
type information for the parameter, a comma, 0 if passed by reference or
1 if passed by value, and a semicolon. The type definition ends with a
semicolon.

For example, this variable definition:

int (*g_pf)();

generates the following code:

.stabs "g_pf:G24=*25=f1",32,0,0,0
.common _g_pf,4,"bss"

The variable defines a new type, 24, which is a pointer to another new
type, 25, which is a function returning int.